PTL 1 discloses a technique of an image processing system which relatively compares frame images of respective video signals simultaneously obtained by a plurality of capturing units, and includes a self-diagnosis unit which performs a self-diagnosis of soundness of the plurality of capturing units according to the comparison result.
Then, PTL 2 discloses a technique of a fault determination unit which causes an exposure amount adjusting unit to change an exposure amount of the capturing unit to be increased or decreased when being in a predetermined operation status, and determines a fault based on whether the brightness of an image of the capturing unit is increased or decreased according to the increase or decrease of the exposure amount.